Slug for a shotgun shell



6, 1962 H. c. MORGAN ETAI. 3,062,145

SLUG FOR A SHOTGUN SHELL Filed April 25, 1960 4 INVENTORS HENRY CLAY MORGAN By AND ALFRED R. GLANTON Hm M91 Patented Nov. 6, 1962 3,062,145 SLUG FOR A SHOTGUN SHELL Henry Clay Morgan, Prattsburg, N.Y., and Alfred R. Glanton, 91 Village Lane, Rochester 10, N.Y. Filed Apr. 25, 1960, Ser. No. 24,494 2 Claims. (Cl. 102-38) The present invention relates to projectiles, and more particularly to an improved projectile or slug which is adapted to be loaded into a shotgun shell for firing from a shotgun.

In many localities it is desirable for a hunter to be able to use a shotgun both in hunting small game and in case of necessity or for convenience, for shooting large game, also, where large game abounds, or is likely to be encountered. For such purposes the shotgun shell is loaded with a single projectile commonly termed a slug, instead of with small balls or shot.

At times, these single projectiles have been made in the form of solid metal balls of standard gauge to fit the bore diameters of shotguns of given gauge. However, since most shotguns had either a modified or a full choke, these balls were made smaller than the greatest choke that would be encountered for a given gauge. These assured that a shell loaded with a single projectile could be used in a shotgun of a given gauge without danger of damage to the barrel, but this solid ball type projectile left much to be desired so far as range and accuracy were concerned.

In an attempt to improve range and accuracy the conventional single projectile is made with a hollowed-out body which is substantially cylindrical in external shape for the major portion of its length and has a solid truncated hemispherically shaped nose. The outside diameter of the slug is made smaller than any possible choke diameter of a gun of a given gauge, because when the gun is fired, the wadding in the shotgun shell is forced by the exploding powder into the hollow of the slug to expand radially the thin cylindrical wall of the slug so that the slug will engage tightly against the inner wall of the barrel as it passes through the barrel.

Where a slug is undersized, however, the problem is to position it coaxially in the shell case, and then to expect it to remain in that position while the forward end of the case is roll-crimped over the adjacent portion of the slug to hold the slug in the case. Furthermore, even if the coaxial position of the slug in the case is achieved initially, the filler wad in the shell directly behind the slug acts as a piston with a force of 8,000 to 10,000 psi. when the shell is fired, and, unless the crimp unrolls evenly, the slug becomes a distorted unsymmetrical mass of soft lead. Thus, the slug will enter the gun barrel out of coaxial alignment therewith; and the distorted mass of lead, as it leaves the barrel, will not follow an accurate trajectory but tends to yaw during flight.

Even where the slug is provided around its periphery with helical grooves, there is still a wide variation between the velocity and direction of different conventional shot gun slugs fired successively at a given target from a given gun.

The primary object of the present invention is to provide a slug for shotgun shells which can be fired with greater accuracy and greater velocity than presently known slugs.

Another object of this invention is to provide a slug for a shotgun shell which can readily be positioned accurately in a coaxial position in the shotgun shell casing.

Another object of this invention is to provide a slug for a shotgun shell which will unroll evenly the crimp of the shell casing as the slug leaves the shell so that the slug may enter the barrel coaxially with the shell case and the chamber.

A still further object of this invention is to provide a shotgun slug so constructed that a minimum amount of lead will be abraded from the slug as it passes through the barrel of the gun.

A further object of the invention is to provide a shotgun shell which is so designed that it will be stable in flight. To this end, a still further object of this invention is to provide an improved shotgun shell constructed so that the expanding gases of firing will cause the top filler wad to lock firmly to the rear of the slug to provide a longer projectile having its center of gravity forward, thereby preventing the slug from tumbling in flight.

Still another object of the invention is to provide an improved shotgun slug of the character described which is simple in its construction and relatively inexpensive to manufacture.

Other object of this invention will be apparent hereinafter from the specification, and from the appended claims, particularly when read in conjunction with the accompanying drawing.

In the drawing:

FIG. 1 is a side elevation of a shotgun slug constructed according to one embodiment of this invention;

FIG. 2 is a front elevation of this shotgun slug;

FIG. 3 is a rear elevation of this shotgun slug;

FIG. 4 is a part side elevation, part axial section, of a shotgun shell loaded with a slug made according to this invention;

FIG. 5 is a side elevation of the shotgun slug after it has been fired and showing the top filler wad locked to the rear end thereof;

FIG. 6 is a shotgun slug constructed according to another embodiment of this invention;

FIG. 7 is a front elevation of this modified shotgun slug; and

FIG. 8 is a rear elevation of this shotgun slug.

In the illustrated embodiments of the invention, the shotgun slug is adapted to be used in a conventional shotgun shell generally denoted at 10. This shell is of the type which has a generally cylindrical metallic base portion 12 and a cylindrical paper or cardboard composition casing 14. The base portion 12 is closed at its bottom and contains the propellant powder. A priming cap 16 is positioned in the center of the bottom of the base 12 to be struck by the firing pin of the gun to ignite the gun powder contained in the base 12. Mounted in the casing 14 in front of the powder chamber are a plurality of conventional filler wads 18 which are made of a relatively hard fiber composition material. These filler wads which are cylindrical in shape, have a diameter slightly greater than the inside diameter of the casing 14 so as to tightly fit therein forward of the powder chamber with appropriate seating pressure. The slug 25 (FIGS. 1 to 3 inclusive) or 50 (FIGS. 6 to 8 inclusive) of this invention is adapted to be placed in the casing 14 in conventional fashion in front of the filler wads 18; and the forward end of the casing 14 is roll-crimped over rearwardly as denoted at 20 to hold the slug in the casing with appropriate crimping pressure.

Referring first to FIGS. 1 through 3, 25 denotes a slug constructed according to one embodiment of this invention. This slug is a single piece of lead or other suitable metal having basically a truncated conical body portion 26 which is of decreasing diameter from front to rear. On and around this body portion are a plurality of equiangularly-spaced helical fins or vanes 28 which extend the length of the conical body portion 26.

The vanes 28 shown are of uniform thickness, from front to rear; and each has a shoulder 31 at its front end which forms an angle with top land 32 of the vane. Although shown as forming an obtuse angle with the top land 32 of the vane the shoulders 31 may form a right angle with each land 32. These vanes 28 increase in height from front to rear because they are arranged on a conical body portion 26 but the top lands 32 of the vanes lie in a cylinder coaxial with the axis of conical body portion 26. The vanes are preferably chamfered or beveled off at their rear ends as denoted at 27 for ease of assembly in the casing 14; but the rear faces 34 of the vanes lie in a plane perpendicular to the axis of the conical body portion 26 and coincident with the plane of the rear face 36 of the body portion.

The outside diameter of the slug, that is, the diameter of the slug across the lands 32 of the vanes 28 is preferably equal to the bore diameter of the barrel. However, if there is any problem of loading a slug of this size in the thin casing of a shell of a given gauge, this outside diameter of the slug can be decreased .005" to .007" without any adverse effects on the performance of the slug.

Integral with the body portion 26 and projecting forwardly therefrom is a truncated hemispherical nose portion 30. The front end 33 of this nose portion is a plane surface perpendicular to the axis of the slug. The diameters of the nose portion 30 at its base and of the front end of the body portion 26 are equal. This diameter is appreciably less than the full choke diameter of a gun barrel of a given gauge so that when the thrust generated by the propellant compresses the slug longitudinally thereby expanding it radially, the expanded diameter at the base of the nose portion of the slug will still be less than the full choke diameter of the barrel. This feature is important because the majority of shotguns have some degree of constriction or choke, and because it is known that even an undersized slug will be expanded by the pressure to the cylinder diameter of the bore. With our construction, a minimum amount of lead will be abraded as the slug passes through the choked portion of the barrel, resulting in greater accuracy in the flight of the slug after it leaves the barrel.

The slug 25 is secured in the casing 14 by the crimp formed on the inside of the casing. The crimp is so formed that its inner edge 38 engages against the shoulder 31 of each vane.

Upon firing of a shotgun shell containing a slug having dimensions such as described, the filler wads 18 are driven against the rear edges 34 of the vanes 28 by the expansion of the generated gases thereby forcing the filler wad into a tight bond with the rear end of the slug; and as the pressure builds up, the vanes 28 are twisted symmetrically in such a manner that the top filler wad is tightly locked between adjacent vanes 28. This automatic union between the symmetrically deformed slug and the filler wad, increases the effective length of the fired slug and places the center of gravity of the wedded mass farther forward. This is due to the fact that the specific density of the filler wad is less than that of the metal of the slug. The placement of the center of gravity forward in the manner described in a non-rotating, nonspinning projectile, such as a shotgun slug insures maximum accuracy in firing.

As the slug 25 moves forward in the shell casing 14, the shoulders 31 of the fins 28 engage the inner edge 38 of the crimp gradually, and unroll or iron out the crimp uniformly as the slug leaves the casing. Thus, the slug which was positioned initially coaxially with the shell and which was located coaxially with the bore of the barrel when the shell was loaded in the gun will be coaxial with the bore of the barrel as it enters it. The vanes 28 are compressed when the slug travels through the choked portion of the barrel, but because of the reduced diameter of the nose and the front end of the conical body portion 26, only the vanes 28 frictionally engage the choked portion of the barrel.

Because of the multitude of bearing surfaces 32 of the vanes, and the circumferential ring surface formed by the symmetrically deformed vanes at the rear end of the slug (see FIG. 5) there is a substantial reduction of frietion between the slug and the barrel; yet necessary and adequate bearing is achieved. With this slug, a minimum amount of lead is abraded therefrom as the slug travels through the choked portion of the barrel.

In FIGS. 6 and 8, a slightly modified form of slug 50 made according to this invention is illustrated. It is also made of a single piece of lead or other suitable metal which will deform when subjected to the pressure of firing of a shotgun. The slug 50 also has a truncated conical body portion 56 which is of decreasing diameter from front to rear. On the body portion 56 are also provided a plurality of equiangularly-spaced fins or vanes 58 which extend helically the length of the conical body portion longitudinally thereof. In this embodiment of the invention, however, a frustro-conical nose portion 60 is formed integrally on the front end of the slug. This frustro-conical portion 60 increases in diameter from front to rear and its rear is of slightly smaller diameter than the front end of the conical body portion 56 to form an annular shoulder 61 around the rear of the nose portion 60.

In this embodiment, each of the vanes 58 also increases in height from front to rear. The top lands 62 of the vanes also lie in a cylindrical surface coaxial with conical body portion 56. The front faces 59 of the vanes are perpendicular to the axis of the conical body portion. The vanes are chamfered at their rear as denoted at 63 for ease in inserting in the shell casing. The rear surface 64 of each vane is, however, here beveled to provide an edge 65 which will cut into the filler wad 18 when the slug is fired thereby facilitating union of wad and slug.

The diameter of the front end of the body portion 56 is the same relative diameter as the front end 26 of the first-described embodiment for a given gauge. When a slug made according to this second embodiment of the invention is inserted into the thin casing 14 of the shell, the casing is again crimped so that its edge 38 engages against the shoulders 59 of the vanes 58 so that the crimp unrolls evenly as the slug 50 leaves the casing.

The slug of this embodiment of the invention is in operation and characteristics similar to the first-described embodiment with the exception that the edges 65 of the slug more easily cut into the top filler wad which may therefore be harder than those conventionally used.

A shotgun slug made according to this invention, when loaded into a shotgun shell containing the proper wad column and crimping pressures will shoot a 40% smaller five shot group (center to center) than any known conventional slug when fired under comparable bench rest conditions, using the same shotgun equipped with suitable sighting devices.

During these tests, shots have been fired using available commercial ammunition and the lead particles which adhered to the bore of the barrel were collected and Weighed on a precision beam balance. Then an equal number of shots were fired from the same gun or guns using the slug of this invention; and again the lead particles adhering to the bore were collected. The results showed that the reduction in leading of the bore amounted to between and 87% in favor of the slugs of the present invention. Thus, there is a substantial reduction of friction between the barrel and a slug made according to the present invention while the slug travels through the gun barrel. This naturally means an increase in muzzle velocity; and an increase in muzzle velocity always means a flatter trajectory resulting in less drop over a given distance.

Since our slug is designed and made geometrically balanced with its outside diameter substantially equal to the bore diameter of the barrel for a given gauge, it is apparent that the center of gravity of the slug will always be coaxial with the shell casing and the gun barrel. With the added length of the filler wad locked to the slug by the automatic union, the center of gravity not only will be an the axis, but forward of the united mass, which is very advantageous in a non-rotating or non-spinning projectile.

In tests, made with slugs constructed according to this invention, the lengths of slugs made according to the present invention, were recovered undistorted after firing and were compared with the length before firing. The same test was made with various conventional slugs. The average reduction in the length of the conventional slugs before and after firing was between 32% and 34%, while the combined length of the compressed slug and attached wadding of slugs made according to the present invention was found to be 107% of the length of the slug before firing. Moreover, a comparison of the bearing lengths of the conventional type slugs with the slugs of the applicants invention showed that the bearing length of conventional slugs decreased between 32% and 34% also While the bearing length of the applicants slug decreased only 3%.

Thus, it is apparent that we have provided an improved shotgun slug which can be used with equal safety and effectiveness in shotguns regardless of the choke of the barrel. Also, we have provided an improved slug which can be fired from a shotgun shell with greater accuracy and over a longer range than those presently known. Moreover, we have provided a slug which can be positioned accurately in a coaxial position in the shotgun cas ing, and which will unroll the crimp evenly as the slug leaves the shell to enter the barrel coaxially thereof. In addition, the slug of the present invention is deformed symmetrically by the expanding gases and a minimum amount of lead is abraded from the slug as it passes through the barrel.

It is also apparent, that the deforming of the slug firmly locks the top filler wad to the rear thereof which provides a longer projectile having its center of gravity not only on the axis of the slug but also at the forward portion thereof.

While the invention has been described in connection with two specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention or the limits of the appended claims.

Having thus described our invention, what we claim is:

l. A slug for a shotgun shell, said slug having a solid frustro-conical body portion of decreasing diameter from front to rear, a plurality of helical vanes projecting externaliy from said body portion and equiangularly spaced about and integral with said body portion, said vanes increasing in height from front to rear, the top lands of said vanes lying in a cylinder coaxial with said body portion, and a dome portion integral with said body portion and projecting beyond the front end of said body portion, the diameter of said dome portion at its rear being less than the outside diameter of said vanes at their front ends, whereby each of said vanes has a shoulder at its front to engage the inner edge of the crimp of a shell in which the slug is fitted to unroll the crimp when the shell is tired.

2. A shotgun shell comprising a hollow cylindrical easing closed at its rear end and open at its front end, the front end of said casing being crimped, said casing having a powder chamber adjacent its rear end, a cylindrical filler wad tightly fitting in said casing in front of the powder chamber, and a slug positioned in said casing in front of the filler wad, said slug having a dome portion at its front and an integral solid frustro-conical body portion behind said dome portion, said body portion being of decreasing diameter from front to rear, and a plurality of helical vanes projecting externally from said body portion and equiangularly spaced about and integral with said body portion, said vanes increasing in height from front to rear, the top lands of said vanes lying in a cylinder eoaxial with said body portion, the cylinder in which the top lands of said vanes lie being of greater diameter than the diameter of the rear end of said dome portion whereby each of said vanes has a shoulder at its front end, said shoulders being positioned in engagement with the rear edge of the crimp in said casing, the rear end of said vanes and said body portion being in engagement with said filler wad whereby when the shell is fired the vanes are twisted at their rear and said filler wad is locked therebetween and whereby upon the firing of the slug from the shell said shoulders iron out the crimp evenly.

References Cited in the file of this patent UNITED STATES PATENTS 1,063,905 Beckmann June 3, 1913 1,288,883 Harvey Dec. 24, 1918 2,573,362 Rouse Oct. 30, 1951 

